Multiple stage catalytic alkylation process



P 1944- c. L. ocoN ET AL MULTIPLE STAGE CATALYTIC ALKYLATION PROCESSFiled May 20, 1940 W n W m m m lE 90 13 \QGQ $5.5 KW w m 5 a5 UQQQ: m Q

Patented Sept. 5, 1944 PATENT omcs MULTIPLE STAGE CATALYTIC AIKYLATIONPROCESS Cecilio L. Ocon and Ernest A. Ocon, Yonkers,

N. Y.; said Cecilio L.

Ernest A. Ocon Ocon assignor to said Application May 20, 1940, SerialNo. 336,246

9 Claims. (0]. 260-6834) This inventlon relates to a method and meansfor producing a superior grade of aviation fraction gasoline of8896'octane number from a catalytic reaction which eiiects the junctionof an isoparaflin and an olefine hydrocarbon molecule to form a productboiling in the'gasoline range. A

Another object of this invention is to produce a higher overall yield ofaviation fraction of the total alkylate from the progressive lowtemperature and low pressure operation.

A further object of this invention is to maintain flexible control ofthe reaction system which allows two or more olefines, i. e., butene andpentene in reaction zones under conditions of temperatures and pressureswhich are conducive to optimum results for each specific reaction. Theseand other objects will be apparent from the following description.

Among the advantages of the present process may be listed a higher yieldof aviation fraction gasoline which is obtained over the yield in asingle stage operation. An additional and greater advantage or thisprocess is that two or more olefine bearing hydrocarbon streams may beprocessed to an advantage in the reaction zone whose temperature is mostsuitable for optimum yields, 1. e., iso-butane and butene may bealkylated or reacted in stage one where the temperature is maintained inthe range of from to F., thus producing approximately 10% more aviationfraction of 2 to 4 octanes higher than if reacted at a highertemperature as is used in stage 3. And similarly a hydrocarbon streamcarrying pentenes as the olefine to be reacted with iso-butane can besatisfactorily treated in the reaction zone operated at a temperaturerange of 20 to 40 F or even at 40 to 70 F., in the 3rd stage. Pentenesdo not require-as low an operating temperature for optimum alkylationTwo ,or more ole-' tion of the total alkylate results from theproolefine concentrations in the first or second reaction zones.

To make this invention easily and more fully understood, an explanationwill now be made with reference to the drawing which illustrates aschematic flow arrangementin a, simplified form. In the drawing the samereference characters are used todenote parts having duplicate forms andfunctions, the subscripts A and Bdenote the sec-- 0nd and third tagesrespectively.

In the apparatus system illustrated, the hydrocarbon stream carryingiso-parafiin and olefine in molecular proportions in the range of 2 to10 molecules of iso-paraflln per moleculeof olefine charged through pipei by pump 2 is joined with a cold acid recycle stream passed from pipe 3and then passed to the first stage refrigeration cooler 4 where thetemperature of the hydrocarbon and acid is further cooled to the desiredlow tempera ture level, for example, l0 to 20 F. Cooler 4 may have aby-pass 5 with a temperature controller 6 to regulate and maintain thetemperature of the streamentering the first stage reaction zone I.

This stream flows to the first stage reaction zone I where a portion orthe iso-parafllns and olefines are reacted in the presence of a catalystsuch as concentrated sulfuric acid (H2804) to form high anti-knockcompounds boiling in the gasoline range. The exothermic heat of reactionwhich is liberated by the joining molecules is controlled by a separateclosed refrigerated coil 8 in the reaction zone itself. The temperaturecon troller 9 regulates the flow of refrigerant into the refrigeratedcoil 8. The eiliuent from the first stage reaction flows through line I0to the first stage acid settler drum H where the hydrocarbon and acidlayers separate. The acid fraction is recycled by pump I! back throughpipe 3 to be joined and mixed with the hydrocarbon charge entering thesystem. The hydrocarbon fraction from the acid settler H is pumped bypump 2A- or flows (it no pump is necessary) through line IA togetherwith cold acid from line 3A to the second stage refrigeration cooler 4Awhere the temperature level for this zone is maintained at a highertemperature in the range of 20 to 40 F., depending upon whichhydrocarbon it is desired to react. Cooler IA may also have a bypass 5Awith a temperature controller 6A. A separate closed refrigerated coil 8Ahaving a temperature controller 9A maintains the desired temperaturelevel in the second stage reaction zone IA by controlling the flow ofrefrigerant to coil 8A in a manner similar'to that described in thefirst stage reaction zone I. The efliuent from the second'stage reactionzone flows through line IIIA to the second stage acid settler IIA whoseobject is analogous to the first stage settler.

The hydrocarbon fraction from the second stage acid settler I IA ispumped by pump 23 and fiows through line IB Jointly with cold acid fromline 33 to the third stage reaction zone 'IB. Cool-'- er 43 may belay-passed entirely through line 53, depending on the operatingtemperature required in zone 13. Reaction "zone 13 is also equipped witha separate internal refrigerated coil 8B having controller 93 fortemperature control. The eiliuents from the third stage reaction zoneflow through line IUB to the third stage acid settler B in which theacid fraction is separated and returned by line 33 and pump IZB to thethird stage system. The temperature level in the third stage reactionzone is maintained in the range of .40 to 70 F. The hydrocarbonellluents from settler IIB flow to the fractionating system (not shown)where the various products are separated.

Provisions are also made for the introduction of additional olefines inintermediate stages of the process. Pentenes and hexenes require higheriso-parafiln to olefine ratios than butenes and propene to produce highquality aviation alkylate. Therefore, as the olefine in the first stageis reduced the pentene or hexene olefines with or without additionaliso-parafiin may be injected into the second or third stage charge linesIA and IB through lines ISA and I3B respectively, thus insuring adequateiso-paraflln olefine ratios in these reaction zones. When pentene andhexeue olefines are to be alkylated, superior quality alkylate isderived with high iso-paraflln olefine ratios in the order of magnitudeof 'l to iso-parailin molecules to one olefine molecule for optimumresults. In addition to the quality of product the acid consumption issomewhat less than when high iso-paramn olefine ratios are maintained inthe reaction zone. The octane number of the aviation fraction of thealkylate is from 2 to 4 octane numbers higher where the above conditionshave been maintained in the reaction zones.

The effluents from the third stage reaction zone are pumped by pump 2Cor by-pased through line I4 to the fractionating system (not shown)where separations are effected in the degree necessitated by the designconditions for each specific charging material. A stream high inisobutane content, say 85%, is separated in the fractionating system andrecycled back to the alkylation system in sufflcient quantity tomaintain the desired iso-butane olefine ratios in the reaction system.Any propane present and the normal butane, aviation alkylate fractionand heavy alkylate fractions are each separated in their respectivefractionating systems.

The catalyst employed in this invention is concentrated sulfuric acid of95 to 98+% (H2804). As the reaction progresses the. acid concentrationbecomes diminished to the point where it'is not economical to continueits use in the'system. Therefore, periodically or continuously aquantity of the reduced concentrated acid is withdrawn from the bottomof the acid settlers through lines I5, ISA and IE3, and replaced by asufflcient quantity of fresh concentrated acid through lines I6, ISA andIBB respectively, to maintain the degree of concentration desired foreconomical operation. The used or spent sulfuric acid which has beenwithdrawn from the system may be pumped to storage for revivification orconcentration and this acid is suitable for this multiple stage reactionsystem is indicated as follows:

Multiple Single stage (3) Stages Volumetric yield .per cent.

82 Octane C. F. R. M 90 The pressures which are employed in the presentprocess are to be sufficient to allow maintenance of the hydrocarbonmaterials in the liquid phase for the temperatures indicated. In generalthis pressure in the reaction vessels may be as low as 5 or it may insome cases be as high as 100 lbs., or more.

Any of the well known refrigerants may be used in the cooling coils,such as propane, nitrous oxide, carbon dioxide, ammonia, etc.

While specific embodiments of the invention and systems for carryingthem into practice have been explained by way of illustration, it is tobe understood that this invention is not to be confined by the exactsteps, pressures, temperatures, proportions or particular devicesmentioned herebefore as typical. The exact size of apparatus andconditions depend upon the analysis of the charging stock, quantities tobe processed and specifications of the final products desired.Instruments, valves, pumps, temperature and pressure indicators,recorders and controllers, meters and other such engineering equipmentare not all shown but it is to be understood that they will be used asrequired and as understood in the art.

Although the present invention is described and illustrated as a threestage alkylation process in the specification and drawing, it is also tobe understood that the scope of this invention is not to be limited to athree stage process as it may be more desirable to use two stages forcertain charging stocks and more than two stages may be desirable forother charging stocks.

Having described our invention what we claim and desire to secure byLetters Patent is as follows:

' 1. A process for producing aviation fraction alkylate which comprisesreacting 3, 4, and 5 carbon atom olefine hydrocarbons with iso-paraiilnhydrocarbons in ratios 01'2 to 10 iso-parafiln molecules to 1 olefinemolecule in the presence of a concentrated sulfuric acid catalyst attemperatures in the range of 10 to 20 IE2, passing said reactedhydrocarbons to a separating zone for .separation of hydrocarboneflluents from said acid catalyst, subjecting said hydrocarbon eflluentsto a second catalytic reaction in a second reaction zone in the presenceof an additional concentrated sulfuric acid catalyst at temperatures inthe range of 20 to 70 F., injecting additional pentens and hexenes intothe second reaction stage with, said hydrocarbon effluents in higheriso-paraflin to olefine ratios than the butenes and propene in the orderof magnitude of 7 to 10 iso-parafiin molecules to 1 olefine molecule,passing said reacted hydrocarbons to a second separating zone,separating and recyclin said additionafacid catalyst to the initialpoint 2. A multistage alkylation process for produc-,

ing aviation motor fuel alkylate, which comprises admixing in an initialstage olefines of 3 to 5 carbon atoms and isobutane with a circulatingence of sulfuric acid' catalyst and maintaining said mixture at arelatively low alkylating temstream of concentrated sulfuric acid madeup of recirculated acid catalyst and fresh acid catalyst, reactingpredominantly 4 carbon atom olefines in said first stage at atemperature in the range of -10 F. to 20 F., separating treatedhydrocarbons from the catalyst, admixing said treated hydrocarbons witha second circulated stream of sulfuric acid catalyst containing freshand recirculated sulfuric acid, and adding additional hydrocarbonscontaining olefines of 5 carbon atoms and iso-parafiins, reacting aremaining portion of olefines and isobutane in said secnd stream at 20F. to 40 F., separating treated hydrocarbons from'the catalyst in saidsecond. stream, admixing treated hydrocarbons separated from said secondstream with a third circulated stream of sulfuric acid catalystcontaining fresh and recirculated sulfuric acid,v reacting remainingolefines and isobutane in said third stream at 40 F. to 70 F., andrecovering the treated hydrocarbons from said third stream.

3. A multistage alkylation process for producing aviation motor fuelalkylate, 'which comprises admixing in aninitial stage olefines of 3 tocarbon atoms and isobutane with a circulating stream of concentratedsulfuric acid made up of recirculated acid catalyst and fresh acidcatalyst, reacting predominantly 4 carbon atom olefines in said firststage at atemperature in the range of F. to 20 F., separating treatedhydrocarbons from the catalyst, admixing said treated hydrocarbons 'witha second circulated stream of sulfuric acid catalyst containing freshand recirculated sulfuric acid, reacting aremaining portion of olefinesand isobutane in said second stream at 20 F. to 40 F., separatingtreated hydrocarbons from the catalyst in said second stream, admixingtreated hydrocarbons separated from said second stream with a thirdcirculated stream of sulfuric acid catalyst containing fresh andrecirculated sulfuric acid, and adding additional hydrocarbonscontaining olefines of 5 and 6 carbon atoms and iso-parafiins,

perature, separating the alkylate thus formed from the acid catalyst andagain contacting said alkylate containing iso-parafilns with olefinichydrocarbons of a greater number of carbon atoms chosen from the groupof the 5 and 6 carbon olefines, the molecular ratio of said isoparafllnsto olefines in said mixture being in excess of 1, in the presence ofsulfuric acid catalyst under alkylating conditions at a temperaturehigher than said first named alkylating temperature to cause analkylation of said is0-para-' flins by said last named olefines andseparating the alkylate thus formed from said acid catalyst.

6. A method for alkylation of iso-paraflin with olefines which comprisescommingling iso-paraifins with olefines comprised predominantly of 4carbon olefines with an alkylating catalyst under alkylating conditionswhereby said 4 carbon olefines alkylate said isc-paraflins, andseparating the catalyst from said alkylate fraction and contacting saidalkylate fraction containing iso-paraflins with an alkylating catalystin the presence of added olefine comprised predominantly of olefinichydrocarbons of molecular weight higher than the said four carbonolefinic hydrocarbons, and alkylating iso-paraflins in said .alkylatehydrocarbon fraction with said higher olefines and separating thealkylate thus formed from said alkylatin'g catlyst.

7. A method of alkylation of iso-paramn with olefines which comprisescommingling iso-parafiins with low. molecular weight olefines and withan alkylating catalyst under alkylating conditions whereby said lowmolecular weight olefines alkylate said iso-parafilns and separatingsaid catalyst from said alkylate fraction and contacting said'alkylatefraction containing iso-paraflins with an alkylating catalyst in thepresence of added olefine of molecular weight higher thansaid lowmolecular weight olefines and alkylating the iso-parafiins present insaid alkylate hydrocarbon fraction with said higher olefines andseparating the alkylate thus formed from said alkylating catalyst.

reacting remaining olefines and isobutane in said third stream at 40 F.to 70 F., and recovering the treated hydrocarbons from said thirdstream.

4. The process for producing alkylation which comprises mixinghydrocarbons taken from the group of the 3, 4, and 5 carbon olefineswith isoparafiins in the presence of a concentrated sulfuric acidcatalyst. under alkylating conditions to form an alkylate by thealkylation of said iso-paraflins with said ole'fines and then contactingiso-paraffins admixed with said alkylate,

with added olefines of a greater number of carbon atoms chosen from thegroup of the 5 and 6 carbon olefines in the presence of concentratedsulfuric acid catalyst, under alkylating conditions, to alkylat saidiso-parafilns with said last named olefins and separating the catalystfrom the alkylate thus formed.

5. A process for producing alkylates which comprises mixing olefineschosen from the group of 3, 4, and 5 carbon olefines with iso-parafilns,the molecular ratio of said iso-paraflins to olefins in the mixturebeingin excess of 1, in the pres- 8. A method of alkylation ofiso-paraflln with. olefines which comprises commingling iso-paraffinswith four carbon olefines and with a liquid alkylating catalyst underalkylating conditions and alkylating said iso-paraflins with said fourcarbon olefines, separating the catalyst from said alkylate fraction andcontacting said alkylate fraction with an alkylating liquid catalystunder alkylating conditions in the presence of added five carbonolefines and alkylating iso-parafllns in said alkylate hydrocarbonsfraction with said five carbon olefines and-separating the alkylate thusformed from said alkylatingcatalyst.

9. A process for alkylating iso-paraflinic hydrocarbons which comprisesreacting butylene with molecular excess of isobutane in the presence ofa liquid alkylating catalyst under alkylating conditions, separating thealkylation catalyst from the alkylate thus formed, commingling saidalkylate with pentene and alkylation catalyst under alkylatingconditions to alkylate -iso-butane present in said alkylate with saidadded pentene and separating the alkylate thus formed from saidalkylation catalyst.

cncruo L. OCON. ERNEST A. OCON.

